Field of the Invention
Tranquilizers have become more and more popularly employed in the treatment of anxiety. Due to the effectiveness of this class of drugs, there has become an increasing availability of drugs and their use has become abused. In non-therapeutic treatments, relatively higher levels of the drugs may be employed. It has therefore become a matter of some importance that economical and rapid means for the determination of the presence of the drug in urine or other body fluid be established.
There are a number of different ways for detecting the presence of a drug in urine. Some of these techniques employ chromatographic techniques such as vapor phase chromatography, thin-layer chromatography, and the like. These techniques depend upon the properties of adsorption of the drug of interest, which allow for the drug to be separated from other materials in the sample being tested. Another group of techniques rely on the ability of a receptor such as an antibody, to distinguish the molecule of interest from other molecules which may be present. These techniques are referred to as immunoassays since they depend on a mammalian immunological response for the production of the antibodies which recognize the compound of interest.
In producing antibodies, one normally conjugates a molecule which resembles the compound of interest to a large molecule which is antigenic. The resulting conjugate is then injected into an animal, normally a domestic animal, to elicit an immunological response with the production of antibodies which recognize the compound of interest.
In producing antibodies, there are a number of considerations as to the usefulness of the antibody composition in an immunoassay. The concentration of useful antibodies must be sufficiently high, so that upon dilution in the assay, there is sufficient antibody to provide for the necessary sensitivity. The binding constant of the antibody should also be high, so that large concentrations of antibodies are not required to ensure a reasonable amount of binding of any of the compound present to the antibody. It should be recognized that normally the concentrations of interest are only a few micrograms per milliliter or less so that one is dealing with extremely small amounts of the compound being assayed.
There is also concern about the degree of specificity for the antibody. Where there are a class of drugs having similar structure and similar properties and the intent is to determine whether any of these drugs are being abused, it is desirable that the antibody be able to detect the metabolites of as many of the class of drugs as possible. That is, the antibody should have reasonably good binding to all of the metabolites, so that concentrations normally encountered in urines with persons using non-therapeutic dosages will give a positive result. With the benzdiazepines, the drugs of interest include diazepam, oxazepam, medazepam, temazepam, des-N-methyl diazepam and chlordiazepoxide.
Description of the Prior Art
U.S. Pat. No. 3,817,837 describes a homogeneous enzyme immunoassay technique, as well as enzyme conjugates for use in the assay. Included among potential conjugates are benzdiazepine derivatives. U.S. Pat. No. 3,609,834 describes a homogeneous spin labeled immunoassay, employing a free radical detector. Included among potential reagents are spin labeled benzdiazepine.